UNAUDITED CONDENSED CONSOLIDATED STATEMENTS OF STOCKHOLDERS' EQUITY - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Retained Earnings	Accumulated Other Comprehensive (Loss) Income
Balance, beginning of period (in shares) at Dec. 31, 2017		78,081,000
Balance, beginning of period at Dec. 31, 2017	$ 655,870	$ 781	$ 152,097	$ 509,697	$ (6,705)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)		(101,000)
Repurchase of common stock	(5,689)	$ (1)	(5,688)
Issuance of common stock for share-based compensation plans (in shares)		566,000
Issuance of common stock for share-based compensation plans	(15,551)	$ 5	(15,556)
Stock-based compensation	15,109		15,109
Cash dividends declared ($0.12 per share)	(2,355)			(2,355)
Other comprehensive income (loss)	4,262				4,262
Net income (loss)	12,200			12,200
Balance, end of period (in shares) at Mar. 31, 2018		78,546,000
Balance, end of period at Mar. 31, 2018	663,846	$ 785	145,962	519,542	(2,443)
Balance, beginning of period (in shares) at Dec. 31, 2017		78,081,000
Balance, beginning of period at Dec. 31, 2017	655,870	$ 781	152,097	509,697	(6,705)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(5,175)
Net income (loss)	(5,796)
Balance, end of period (in shares) at Sep. 30, 2018		78,816,000
Balance, end of period at Sep. 30, 2018	620,855	$ 788	135,132	496,815	(11,880)
Balance, beginning of period (in shares) at Mar. 31, 2018		78,546,000
Balance, beginning of period at Mar. 31, 2018	663,846	$ 785	145,962	519,542	(2,443)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)		(171,000)
Repurchase of common stock	(10,181)	$ (2)	(10,179)
Issuance of common stock for share-based compensation plans (in shares)		358,000
Issuance of common stock for share-based compensation plans	(11,391)	$ 4	(11,395)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		15,000
Issuance of common stock under Employee Stock Purchase Plan	849		849
Stock-based compensation	16,163		16,163
Cash dividends declared ($0.12 per share)	(2,364)			(2,364)
Other comprehensive income (loss)	(7,341)				(7,341)
Net income (loss)	(10,409)			(10,409)
Balance, end of period (in shares) at Jun. 30, 2018		78,748,000
Balance, end of period at Jun. 30, 2018	639,172	$ 787	141,400	506,769	(9,784)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)		(242,000)
Repurchase of common stock	(14,279)	$ (2)	(14,277)
Issuance of common stock for share-based compensation plans (in shares)		310,000
Issuance of common stock for share-based compensation plans	(8,396)	$ 3	(8,399)
Stock-based compensation	16,408		16,408
Cash dividends declared ($0.12 per share)	(2,367)			(2,367)
Other comprehensive income (loss)	(2,096)				(2,096)
Net income (loss)	(7,587)			(7,587)
Balance, end of period (in shares) at Sep. 30, 2018		78,816,000
Balance, end of period at Sep. 30, 2018	$ 620,855	$ 788	135,132	496,815	(11,880)
Balance, beginning of period (in shares) at Dec. 31, 2018	78,526,000	78,526,000
Balance, beginning of period at Dec. 31, 2018	$ 621,531	$ 785	123,205	510,863	(13,322)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)		(144,000)
Repurchase of common stock	(7,587)	$ (1)	(7,586)
Issuance of common stock for share-based compensation plans (in shares)		514,000
Issuance of common stock for share-based compensation plans	(14,838)	$ 5	(14,843)
Stock-based compensation	18,406		18,406
Cash dividends declared ($0.12 per share)	(2,367)			(2,367)
Other comprehensive income (loss)	2,001				2,001
Net income (loss)	(28,717)			(28,717)
Balance, end of period (in shares) at Mar. 31, 2019		78,896,000
Balance, end of period at Mar. 31, 2019	$ 588,429	$ 789	119,182	479,779	(11,321)
Balance, beginning of period (in shares) at Dec. 31, 2018	78,526,000	78,526,000
Balance, beginning of period at Dec. 31, 2018	$ 621,531	$ 785	123,205	510,863	(13,322)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Other comprehensive income (loss)	(587)
Net income (loss)	$ (91,351)
Balance, end of period (in shares) at Sep. 30, 2019	79,324,000	79,324,000
Balance, end of period at Sep. 30, 2019	$ 528,832	$ 793	129,559	412,389	(13,909)
Balance, beginning of period (in shares) at Mar. 31, 2019		78,896,000
Balance, beginning of period at Mar. 31, 2019	588,429	$ 789	119,182	479,779	(11,321)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)		(88,000)
Repurchase of common stock	(6,302)	$ (1)	(6,301)
Issuance of common stock for share-based compensation plans (in shares)		320,000
Issuance of common stock for share-based compensation plans	(11,214)	$ 3	(11,217)
Issuance of common stock under Employee Stock Purchase Plan (in shares)		16,000
Issuance of common stock under Employee Stock Purchase Plan	1,103		1,103
Stock-based compensation	20,113		20,113
Cash dividends declared ($0.12 per share)	(2,375)			(2,375)
Other comprehensive income (loss)	(171)				(171)
Net income (loss)	(32,296)			(32,296)
Balance, end of period (in shares) at Jun. 30, 2019		79,144,000
Balance, end of period at Jun. 30, 2019	557,287	$ 791	122,880	445,108	(11,492)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Repurchase of common stock (in shares)		(88,000)
Repurchase of common stock	(6,397)	$ (1)	(6,396)
Issuance of common stock for share-based compensation plans (in shares)		268,000
Issuance of common stock for share-based compensation plans	(8,801)	$ 3	(8,804)
Stock-based compensation	21,879		21,879
Cash dividends declared ($0.12 per share)	(2,381)			(2,381)
Other comprehensive income (loss)	(2,417)				(2,417)
Net income (loss)	$ (30,338)			(30,338)
Balance, end of period (in shares) at Sep. 30, 2019	79,324,000	79,324,000
Balance, end of period at Sep. 30, 2019	$ 528,832	$ 793	$ 129,559	$ 412,389	$ (13,909)